interpret primaryjoin where the actual FK/PK column is inside a binary expression or similar

[Andrey Popp]

Currently SQLAlchemy doesn't allow to map relationships which have primaryjoin condition like this:

a.c.b_id + 2 == b.c.id

It just can't figure out the direction of relationships even if I supply a.c.b_id + 2 as foreign_keys element.

dupe of

[Andrey Popp]

Please see attached test case for more info regarding issue. I think this is good enhancement to SQLAlchemy.

[Andrey Popp]

Test case

[Andrey Popp]

Attached second version of test case there foreign_keys contains column and not expression.

[Mike Bayer]

this is really a dupe of #610.

You can do it like this:

mapper(A, a, {
    "b": relationship(
        B,
        primaryjoin=a.c.b_id + 2 == b.c.id,
        _local_remote_pairs = [b.c.id)]((a.c.b_id,),
        foreign_keys=a.c.b_id,
        viewonly=True)
    })

[Andrey Popp]

Thanks, somehow I didn't spot _local_remote_pairs in RelationshipProperty constructors arguments.

[Mike Bayer]

its not entirely public. I give it to people when they ask.